In the explosives/ flammable items section everything flammable or explosive seems to be a big no for being able to be in baggage. I work for a regional airline, and coals may be considered Hazmat, flammable materials. check with the airline you are flying with to see if they ship that as cargo. some airlines will ship your bags as cargo, i have seen it myself, so you can avoid getting your stuff taken away. be carefull, the TSA is very good at finding stuff. Saw them pull a bottle of 180 proof liquor out of a bag. Hazmat all the way right thier.